This article describes method of thermal properties analyzes that was developed by Anton Paar in collaboration with the group around Prof. Krüger from the University of Luxembourg. The method uses monitoring of changes of optical properties under the influence of thermal excitation. Optical response is a change in the refractive index. A mathematical relationship between the refractive index and the density of a substance makes possible to calculate a temperature parameter such as the coefficient of thermal expansion. Then, one can use temperature dependence of this parameter to determine the regions in which phase transitions occur (melting, crystallization, vitrification, etc.) and curve of time dependence of the coefficient of thermal expansion can be used to investigate curing, polymerization or ageing processes. Possible application areas: QC of raw, intermediate, and final products, analysis of the influence of humidity and on curing and aging process of materials, determination of the glass transition point of cured adhesives and polymers, investigating of volume shrinkage caused by curing or polymerization, and often in food processing industry.